The present invention relates to a time code signal generator used in a time code signal recording apparatus.
Hitherto, when recording by a magnetic recording and reproducing apparatus, it is typical to record video signal in real time. In other words, 60 minutes worth of video signals are recorded in 60 minutes. Such prior art is disclosed, for example, in U.S. Pat. No. 4,503,470.
FIG. 4 shows a constitution of a time code signal generator for a time code recording apparatus of a conventional magnetic recording and reproducing apparatus. In FIG. 4, a time code preset circuit 20 generates an initial value of a time code. A system control circuit 2 generates a mode signal 9 for setting the operating state of recording and reproducing. In this case, the mode signal 9 includes information indicating that the recording speed is the same speed as the reproducing speed.
The initial value of the time code generated in the time code preset circuit 20, the mode signal 9, and control signal 21 are put into a time code counter 22. As the control signal 21, usually, a pulse signal changing in the frame period of video signal is used. This control signal changes, in the case of an NTSC signal, in {fraction (1/30)} second.
The time code counter 22 counts every time the control signal 21 changes from the initial value, that is, every {fraction (1/30)} second, and issues time code information. The time code information is put into a time code output circuit 23. In this circuit, in order to record in a recording track, it is converted into a one-bit serial signal, and is sent to a time code recording circuit (not shown) as recording time code 5.
This is a prior art recording at the same speed as the reproducing speed.
Recently, however, for non-linear editing, video signals are often recorded in a hard disk or transmitted through a network, and in such a case it is sometimes desirable to record or transmit in a shorter time than the real time, for example, in one-fourth time. In this case, the video signals are recorded, reproduced or transmitted at a speed of four times. Naturally, the same is required when dubbing between magnetic recording and reproducing apparatuses.
In the case of NTSC, four frames are recorded, reproduced or transmitted in {fraction (1/30)} second. In such time code recording apparatus of magnetic recording and reproducing apparatus, it is required to increase the signal processing speed and shorten the time necessary for recording, and a magnetic recording and reproducing apparatus which provides simplified recording of all information securely and at high speed is desirable.
However, the existing time code recording apparatus is limited to an apparatus for recording at normal speed . To realize high speed recording of N times, it is theoretically possible to increase the tape speed N times and increase the oscillation frequency of the time code generator N times, but since the operating frequency is a high speed, the operation timing is critical, and the existing circuit does not operate normally.
A time code signal generator is applicable to high speed recording More specifically, an apparatus is capable of recording while maintaining the reliability of time code information necessary for a video signal (specified timing and continuity) without radically changing the operating speed of the conventional circuit.
For generating a corresponding time code when recording video signals at a speed of N times, included are counting means for incrementing the time code value in N frame steps from the reference time code value of initial value, correcting means for interpolating the skipped time code value, and means for arraying the incremented time code value and interpolated time code value in a specified sequence, and issuing serially. Hence, N times speed time code corresponding to N times speed video signal can be generated securely.